1. Field of Invention
The present invention relates to an improved water heater having several resistive heating elements of different power factors and wherein these elements are controlled by a control circuit whereby to operate at different periods of a day in order to reduce the power loads on an electrical distribution network during peak electrical demand periods of the day.
2. Description of Prior Art
It is well established that 80% of the population is satisfied with a hot water tank having a 40 Imperial gallon capacity. It is also known that of the remaining 20%, 19% are satisfied with a 60 Imp. gal. tank capacity, and 1% with 100 Imp. gal. tank capacity. Electrical hot water tanks are heated with resistive heating elements having a power factor rating of 3000 or 4500W, and these heating elements are operative as soon as the consumer utilizes 4 gallons of hot water from the reservoir. Accordingly, during peak hours when hot water is used, normally in certain periods of time between 6:00 a.m. and 9:00 p.m., there is an excessive demand of power from the distribution network. This is a problem that electrical utilities have faced for a long time and have yet not found an adequate solution. Various devices have been developed, but not utilized effectively to cut out entirely specific electrical appliances during peak demand periods in order to alleviate the problem. However, cutting out electrical appliances, such as hot water heating tanks, is not a popular solution and can often have drastic effects. Systems were developed to shut off such devices during these peak demand periods, for example, the use of a transmission signal on transmission cables, or else the transmission of radio frequencies by local radio stations to actuate electronic switching circuits coupled to the hot water heaters to shut them off and reactivate them. One can imagine the problems that can occur whenever RF signals erroneously trigger the electronic circuits to shut off appliances or when persons are deprived of essential applicances.